Figure 3.

Canonical Wnt signaling mechanism. (1) Wnts bind to Frizzled (Fz) transmembrane receptors and low-density lipoprotein receptor-related protein (Lrp) co-receptors (2) triggering the dissolution of the 'β-catenin destruction complex', resulting in (3) β-catenin not being marked for degradation (asterisk) thereby accumulating in the cytoplasm and (4) translocating to the nucleus. (5) Once in the nucleus, β-catenin binds to the T cell factor/lymphoid enhancer factor (Tcf/Lef) family of DNA-binding factors to form a transcriptional complex that binds target promoter sequences via a specific DNA-binding domain in TCFs, mediating Wnt target gene expression. APC, adenomatous polyposis coli.